Pezza, Roberto Jose

Roberto Jose Pezza, Ph.D.

Everybody knows you can break your arm, but most people are unaware that you can break your DNA, too. And fewer still know that DNA can be repaired.

Deoxyribonucleic acid, or DNA, is a string of four different chemicals that make up the library of you. The order of chemicals in your DNA is the determining factor in the color of your hair, how tall you can grow and how your body makes proteins and other chemicals. And you don’t just have one piece of DNA – there’s a copy in almost every cell in your body.

Damage to DNA can cause or contribute to a number of diseases, and in my lab, we’re studying how breaks and repairs at different points in life can affect health. DNA that is cut or malformed in the embryonic stage can cause birth defects and lead to Down syndrome or Turner syndrome. If DNA is damaged after birth, it can sometimes cause cancer.

We’re studying a system that repairs a specific kind of DNA cut and how some repairs are good and others cause problems. By understanding how the system works, we hope to better diagnose disease and find ways to treat or prevent birth defects and some kinds of cancer.

EducationB.S., National University of Cordoba, Argentina, 1997
M.S., National University of Cordoba, Argentina, 1997
Ph.D., National University of Cordoba, Argentina, 2002
Research Fellow, National Institutes of Health, Bethesda, MD, 2007-2009

Honors and Awards1997 Scholarship, National University of Cordoba, State of Cordoba Scientific Research Council (CONICOR), Argentina
1998-2000 Fellowship (for initial training in research), National Research Council (CONICET), Argentina
2000-2002 Fellowship, National Research Council (CONICET) Argentina
2002-2004 Research Excellence Award, National Universities and National Educational Council, Argentina
2003-2007 Visiting Fellow, National Institutes of Health, Bethesda, MD
2007-2009 Research Fellow, National Institutes of Health
2007 Fellows Award for Research Excellence, National Institutes of Health

Joined OMRF Scientific Staff in 2009.

Chromosome aneuploidies are the leading cause of infertility and birth defects in humans. They result from errors in the segregation of homologous chromosomes (HCs) during gametogenesis. The proper segregation of chromosomes is ensured by meiotic homolog recombination (HR). It begins with the introduction of DNA double-strand breaks (DSBs) followed by their repair using the intact DNA of a HCs as template. This leads to a temporal association of the HCs in pairs that ensures their orderly segregation to opposite poles of dividing nuclei so that each gamete receives one (and only one) homolog of each pair. The homologs that fail to synapse segregate randomly, having 50% chances to go into the same daughter cell. Consequently, mutations that reduce or abolish recombination are invariably associated with gross abnormalities in chromosome segregation. An estimated 10 to 30% of fertilized human eggs have the wrong number of chromosomes resulting in at least 5% of conceptions being aneuploid. Most of them abort before term making aneuploidy the leading known cause of pregnancy loss. Those who survive face devastating consequences, including developmental disabilities and mental retardation.

The field of homologous recombination faces exciting challenges. One of the biggest tests will be to connect the dots between the biochemical function of proteins involved in HR and their in vivo role.

My laboratory studies the bases involved in the repair of DSBs and HCs synapses in mouse. We use a combination of different approaches ranging from the reconstruction of in vitro systems using purified proteins to the generation of genetically modified mice. Our goal is to uncover the fundamental molecular mechanisms regulating the process of homologous recognition and the proper segregation of HCs.